European Union regulators accused a group of 149 banks, including BNP Paribas and Societe Generale, with breaking EU rules over a fee agreement to handle debit-card transactions.
The European Commission said the accord by the members of the Paris-based Groupement des Cartes Bancaires was not exempt from rules that ban pricing agreements between competitors.
The tariffs hindered the issuing of cards by new entrants by granting preferential fees for group members, the commission said.
'The commission's preliminary view is that the tariffs have both the object and the effect of restricting competition,' the Brussels-based regulator said.
The EU's move may force member banks to find another way to pay for managing transactions on cards in the Groupement des Cartes Bancaires network, used to make Euro236.8 billion ($2.3 trillion) in payments last year.
The group had a chance to respond to the commission's objections before a final ruling in the case, the regulator said.
Francoise Fanari, spokeswoman for Groupement des Cartes Bancaires, declined to comment.
Yesterday's announcement is part of the EU's wider investigation of banking fees that began in June 2004.
Competition Commissioner Neelie Kroes said on Monday that the retail banking industry should 'examine their practices and improve them where possible'.
She accused MasterCard on June 30 of restricting competition between banks by setting minimum fees for retailers.
'The Cartes Bancaires probe is part of the trend of the banks being scrutinised over their fees,' said Jean-Pierre Lambert, an analyst at Keefe, Bruyette & Woods.
'It's part of the commission's drive to create a pan-European payment scheme,' Mr Lambert said.